A switched reluctance rotating machine does not include a permanent magnet or a winding wire in a rotor and is adapted to be operated by magnetic attraction generated between the rotor and a stator. The switched reluctance rotating machine has problems of vibration, noise, and the like in principle. However, the switched reluctance rotating machine has a simple and solid structure, can also withstand high-speed rotation, and is inexpensive since the switched reluctance rotating machine does not require expensive permanent magnets such as neodymium magnets. Accordingly, in recent years, research and development for the switched reluctance rotating machine as a rotating machine, which is inexpensive and excellent in reliability, has progressed for a practical use.
As part of the progress to the practical use, a method of making the switched reluctance rotating machine have a double-stator structure is proposed in order to improve the performance of the switched reluctance rotating machine.
Patent Document 1 discloses a double-stator motor that includes an annular rotor, an inner stator disposed inside the rotor, and an outer stator disposed outside the rotor.
Coils, which have phases corresponding to each other, of the inner and outer stators are connected to each other in series. According to this structure, since it is possible to align currents flowing in the coils, which correspond to the respective phases, of both the inner and outer stators, it is possible to make magnetomotive forces of both the inner and outer stators equal. Accordingly, since magnetic flux, which is generated by the inner and outer stators and interlinked with each other, is reduced, it is possible to increase reluctance torque.